Help Me Understand Why Tap to Focus

[Drestin Black]

Every camera I am aware of has auto focus. I'm talking from the cheapest to my Nikon D5 has auto-focus. In fact, it's a constant battle to have the bestest auto focus around, making it fast and working in lower light and more focus points of varying types. drones prior to the Mavic pro (and now P4P) had focus at infinity which worked just fine.

Suddenly I'm reading reviews where you take photos and video while flying Only to find out Afterwards that they are out of focus, you can't even SEE that you are in/out of focus while taking them. Huh?! Video should do real time focus all the time. Still should do focus when you engage the shutter, to emulate how a DSL, for example, works. Am I not getting how Tap To Focus on these new drones works? Seems like a major step back here. To this point, I take it out, I click the button and I get razor sharp photos and videos EVERY time. I've literally never had an out of focus shot (other than motion/low light issues, unrelated to this topic). Now I have to worry that I go home thinking I've got my shots (they looked fine at the time) to find out I've got gigs of blurry messes?

 

[GavinW]

Good question! I'd like to know as well.

 

[Raptorman0909]

OK, so just what part of the scene should be in focus? If you are flying above, say, 50 feet and you focus on a spot about 200 feet away you are pretty much assured that the entire FOV will be well focused. If you are closer to an object, say 5 feet, do you want the camera to be focused at 5 feet or 200 feet? If you say 5 feet how do you make sure the camera knows the spot you are focusing on is 5 feet and not 200 feet?

It would probably be nice if there was a focus mode that assumed the operator just wanted more or less infinity focus but once again, what do you do if the object in mind is 5 feet away?

You can't compare the focus performance with cameras that have very small sensors like smart phones with cameras that have sensors the size of DSLR and M43 cameras -- an entirely different game and the larger the sensor the bigger that issue becomes. With really small sensors the lens is typically in the f/2-f/2.8 range and is fixed at that aperture, but because the sensor is so small the DOF is still pretty high. With larger sensors you need to stop down to get the same DOF.

If you do not want to bother with all of that then stay with the drones with fixed aperture and tiny sensors like the GoPro. But, if you want to be able to have greater control of DOF and other parameters then you are going to go with larger sensors and will then need to stay on top of things you don't have to worry about with smaller sensors.


Brian

 

[AmirChar]

For the photographers out there... I am guessing with this camera and the F range, you should be able to do things like get close to a church steeple for example and focus on it and get the background to be blurry if you want?

 

[tcope]

When you point a DSLR camera at an entire landscape, what does it focus on? Higher end cameras _allow_ multiple focus points and, basically, tap to focus. Both of their pros and cons. You can cane good depth of field with tap to focus. Also, those photos you see that are out of focus... it's because the operator did not use he camera correctly. Don't blame the camera. Once the objects are about 50' away, one tap will turn the focus to infinity and you are good to go.

 

[RC Madman]

To me it is the biggest fail of the Mavic although I am sure one may be able to get use to it. Personally I think AF is a must have on a drone.

 

[CactusJackSlade]

To me it is the biggest fail of the Mavic although I am sure one may be able to get use to it. Personally I think AF is a must have on a drone.

I would agree there should be a default somewhere so you can always be assured of infinity focus... Especially on a smaller screen one might not notice a slightly out of focus for the entire flight. That would be a bummer... maybe some of the owners can pipe in and see if they have ruined any shoots due to out of focus?

Simple.... when you take off, automatically goes to the infinity setting... THEN if you want tap to focus, another on screen button or something?

 

[thedjtec]

I would agree there should be a default somewhere so you can always be assured of infinity focus... Especially on a smaller screen one might not notice a slightly out of focus for the entire flight. That would be a bummer... maybe some of the owners can pipe in and see if they have ruined any shoots due to out of focus?

Simple.... when you take off, automatically goes to the infinity setting... THEN if you want tap to focus, another on screen button or something?

I agree. DJI Needs to let us map C1/C2 to infinite focus. I'm actually surprised we can't yet

 

[Raptorman0909]

The problem with an infinity focus on a camera that is not fixed focus is that it's pretty hard to have the lens shift to the correct spot for infinity -- there's too many variables and the sensor to determine lens position isn't nearly accurate enough to do that properly. I could be possible to calibrate the lens for infinity but once again the lens position sensor isn't likely to be precise enough to make sure it goes there every time.

Again, if not having to focus is a must for you then don't buy the P4P or Mavic or Inspire -- stay with older DJI drones or maybe the Karma. As for me, I'll take the additional control and creative options and live with the need to focus.


Brian

 

[RC Madman]

The problem with an infinity focus on a camera that is not fixed focus is that it's pretty hard to have the lens shift to the correct spot for infinity -- there's too many variables and the sensor to determine lens position isn't nearly accurate enough to do that properly. I could be possible to calibrate the lens for infinity but once again the lens position sensor isn't likely to be precise enough to make sure it goes there every time.

Again, if not having to focus is a must for you then don't buy the P4P or Mavic or Inspire -- stay with older DJI drones or maybe the Karma. As for me, I'll take the additional control and creative options and live with the need to focus.


Brian

Do you own a Mavic or P4P? Can you tell us how well that is working for you? I have read a few reviews that the biggest issue with the Mavic was the tap to focus?

 

[stealle]

OK, so just what part of the scene should be in focus? If you are flying above, say, 50 feet and you focus on a spot about 200 feet away you are pretty much assured that the entire FOV will be well focused. If you are closer to an object, say 5 feet, do you want the camera to be focused at 5 feet or 200 feet? If you say 5 feet how do you make sure the camera knows the spot you are focusing on is 5 feet and not 200 feet?

It would probably be nice if there was a focus mode that assumed the operator just wanted more or less infinity focus but once again, what do you do if the object in mind is 5 feet away?

How often do you record drone video footage of something 5 feet away? Most people will say rarely. How often are you recording video footage greater than 50 feet away? Most people will say, most of the time. So, to me it seems like at the very least, the Mavic and P4P should default to a focus of infinity upon power up. As it is, it seems to default to a closer focus. Another nice option would be to focus on whatever is in the center of the screen automatically when you tap the record button. And, make these OPTIONS in the DJI Go app.

 

[Tron_X]

Cameras such as these are dependent on contrast detection for autofocus. As such, the camera must "hunt" in order to lock onto focus. Changes in scenery during video recording would trigger constant hunting which would deliver worse results than simply remembering to focus when composing the shot.

The other consideration is the sensor size. As the sensor size increases depth of field decreases for a given aperture. So setting the camera to infinity focus would not allow for sharp focus on nearby objects. It's a lot easier to cheat with infinity focus on cameras with minuscule sensors like the P4, P3 and action cameras because their depth of field is tremendous, even at wide apertures.

 

[BigAl07]

Keep in mind that the P4Pro has a "Professional" (at least to a small degree) in mind and it's a nice feature to have if you're going for a specific type of shot. Is it perfect for every shot? Absolutely not but it will allow for some very creative shots that are not possible with AF or other "easy buttons" with lower end cameras.

Those who know how to work a camera will have a field day with the P4P.

 

[syotr]

Autofocus is the new killer feature that will make you want to buy the P5. It will be announced right after your P4p ships in June....

 

[Drestin Black]

Cameras such as these are dependent on contrast detection for autofocus. As such, the camera must "hunt" in order to lock onto focus. Changes in scenery during video recording would trigger constant hunting which would deliver worse results than simply remembering to focus when composing the shot.

The other consideration is the sensor size. As the sensor size increases depth of field decreases for a given aperture. So setting the camera to infinity focus would not allow for sharp focus on nearby objects. It's a lot easier to cheat with infinity focus on cameras with minuscule sensors like the P4, P3 and action cameras because their depth of field is tremendous, even at wide apertures.

Thank you! That explains it very well.

I am a professional photographer, I have only shot cameras with DX and FX sized sensors. I was unaware that tiny sensors produce tremendous depth of field. That really explains how they get away with it and why moving to a larger sensor would require this change.

Why did they do it on the Mavic Pro when it has the same minuscule sensor as he P4?


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[Drestin Black]

I'm trying to figure something out: when I take a still photo this tap to focus is really no different than when I press the shutter half way and it auto focuses before I press fully to take a photo, not a big deal.

Most of the video that I take is not while hovering of stationary objects, I'd guess that well over 75% of the video I shoot is while both the drone and targets are moving. Or at least the drone is moving around, including changing the distance to subject; that will require focus change.

Does this mean, while shooting constant video, that we have to keep tapping the screen the keep updating focus as we move and "see" different objects? Am I going to have to constantly focus where with all prior models I flew around after clicking "Start video" and could get twenty minutes of perfectly sharp video all by itself.

I understand the benefits of this upgraded camera, I myself begged for such things - but I didn't realize the cost. I may end up keeping one of my P4s for video only due to the convenience of sharp focus 100% of the time automatically and use the P4Pro for still photos only?

Man, this is going to take some investigating ... could sour things ;(


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[smiller]

Does this mean, while shooting constant video, that we have to keep tapping the screen the keep updating focus as we move and "see" different objects?

No, not at all. As was mentioned earlier in the vast majority of flight modes DOF will be sufficient that you can simply tap-focus on infinity at take-off and then be done with it for the entire flight. I suppose that DJI could (and may yet) make an infinity focus setting the default on power-up for those who forget to check it, but beyond that it's really not a problem in operation unless one wants to make it so. The creative advantages of having an actual iris and settable focus more than make up for the trivial task of remembering to make a single focus tap on the screen at the beginning of flight.

 

[Drestin Black]

No, not at all. As was mentioned earlier in the vast majority of flight modes DOF will be sufficient that you can simply tap-focus on infinity at take-off and then be done with it for the entire flight. I suppose that DJI could (and may yet) make an infinity focus setting the default on power-up for those who forget to check it, but beyond that it's really not a problem in operation unless one wants to make it so. The creative advantages of having an actual iris and settable focus more than make up for the trivial task of remembering to make a single focus tap on the screen at the beginning of flight.

If that is all I have to do then you are right. No big deal. I would strongly agree that it should default to infinity focus upon launch until changed. It's be nice not to have to add yet one more thing to the preflight check list.


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[Tron_X]

Thank you! That explains it very well.

Why did they do it on the Mavic Pro when it has the same minuscule sensor as he P4?

Sent from my iPad using PhantomPilots

The Mavic Pro has a faster lens and a narrower field of view which decreases depth of field to some extent vs the P4. I'm convinced it's probably just an off-the-shelf cell phone lens module stuffed in that little gimbal. Phone cameras use the same size chip and have had AF capability for years.

 

[Raptorman0909]

Do you own a Mavic or P4P? Can you tell us how well that is working for you? I have read a few reviews that the biggest issue with the Mavic was the tap to focus?

I do have the Mavic on order but have not yet received it and may well cancel the order, perhaps to buy the P4P instead.

There were a lot of focus issues at first with the Mavic but that was because the reviewers did not know about tap to focus, but in just a few days other reviewers demonstrated the tap to focus thing and since then most of the video from the Mavic has been pretty good. I should mention that tap to focus is NOT new and has been around with DJI drones since at least the Inspire 1 drone. I have the Inspire 1 Pro drone and did a video on tap to focus a while back.

The bottom line is that as DJI has improved the quality of there drones they have also improved the quality of the drone cameras and that has made them closer to prosumer grade cameras that have long had lenses that required focusing. The early drones with tiny image sensors tend to have fixed focus and because the sensors are very small they still get pretty decent DOF even when the lens is locked at f/2.8 or even f/2.0. But, if you want better images and videos you need to go with larger sensors but doing that tend to require a more professional approach and technique. The P4P with 1 inch sensor, which is actually as big or bigger than the M43 sensors and just a tad smaller than APC sized DSLR sensors introduces many improvements but also a greater awareness of technique including focusing.

If you are OK with doing these extra things these newer drone cameras offer much greater image quality potential but if you'd rather just not have to worry about it then perhaps the older drones with smaller sensors and fixed focus might be preferred. The new GoPro Karma uses a small sensor and fixed focus lens and may be a good choice for the fly and forget crowd, but, frankly, the older P4 is probably the better choice.


Brian